rats and mice

LABORATORY ANIMAL MEDICINE AND SCIENCE SERIES II

RATS AND MICE:Biology

V-9041

David M. Moore, MS, DVM, Diplomate ACLAM

Office of Animal ResourcesVirginia Polytechnic Institute and State University

and theVirginia-Maryland Regional College of Veterinary Medicine

Blacksburg, Virginia

The Laboratory Animal Medicine and Science - Series II - has been developed by the AutotutorialCommittee of the

American College of Laboratory Animal Medicine (ACLAM): G. L. VanHoosier, Jr., DVM ChairG. L. Borkowski, DVM; K. M. Boschert, DVM; J. F. Harwell, Jr., DVM; J. M. Linn, DVM;C. W. McPherson, DVM; A. F. Moreland; DVM; G. M. Otto, DVM; C. A. Pekow, DVM.Instructional development and production assistance provided by Barbara Macfadden.

The development of this program is supported by a grant fromDuPont Merck Pharmaceutical Company.

Laboratory Animal Medicine and Science _ Series IIis produced by the

Health Sciences Center for Educational ResourcesUniversity of Washington

2 LABORATORY ANIMAL MEDICINE AND SCIENCE - SERIES II

University of WashingtonHealth Sciences Center for Educational ResourcesBox 357161Seattle, WA 98195 _ 206/685-1156

ISBN: 1-55910-051-6

Copyright © 2000by the University of Washington Health Sciences Center forEducational Resources and the American College of LaboratoryAnimal Medicine

All rights reserved

Printed in the United States of America

V-9041 - RATS AND MICE: Biology 3

AUDIENCE Veterinary and biomedical students, animal care technicians, andresearch investigators.

GOAL To familiarize the viewer with the taxonomy, anatomy, physiology,nutrition, and behavior of laboratory rats and mice.

OBJECTIVES At the conclusion of this program, you should be able to:1. name genus and species of the laboratory rat and the laboratory

mouse.2. list four reasons why rats and mice are commonly selected and

used in research.3. describe the distinctive anatomical features of rats and mice.4. give the approximate life span of the rat and the mouse.5. list two forms of rodent diet.6. describe the methods available for evaluating the stages of the

reproductive cycle and assuring that mating has taken place.7. recognize common behavioral traits in laboratory rats and mice.


1. Series Laboratory Animal Medicine and Science _ Series II

2. Program title RATS AND MICE: Biology

3. Objectives At the conclusion of this program, you should be able to:_ name genus and species of the laboratory rat and the laboratory

mouse._ list four reasons why rats and mice are commonly selected and

used in research._ describe the distinctive anatomical features of rats and mice._ give the approximate life span of the rat and the mouse._ list two forms of rodent diet._ describe the methods available for evaluating the stages of the

reproductive cycle and ensuring that mating has taken place._ recognize common behavioral traits in laboratory rats and mice.

4. Section title INTRODUCTION

5. Taxonomy Rats and mice are grouped in the order Rodentia, suborderMyomorpha, family Muridae. The laboratory rat was derived from thewild Norway rat Rattus norvegicus. The laboratory mouse wasdeveloped mainly from the western European house mouse, and thetaxonomic designation, Mus musculus, is a composite designation forseveral interbreeding species.

6. Numbers used

Rats and mice are the most commonly usedanimals in research and testing. This chart showsapproximate numbers used in recent years (4).Rats and mice account for approximately 90% of allmammals used in scientific endeavors.

7. Attributes for The commercial availability of rats and mice, plus their small size, highreproductive

research rate, and minimal costs for purchase and maintenance, have madethem the most studied and perhaps best understood laboratory animalspecies. In addition, they are also well understood and characterizedanatomically, physiologically, and genetically.


8. More attributes Several stocks of rats and mice have withstood the process ofinbreeding, allowing the commercial production of a large variety ofinbred strains and providing the researcher with thousands ofgenetically similar individuals. A large number of mutant strains andstocks, with naturally occurring anatomical, physiological, orbiochemical diseases, have been developed as animal models forsimilar conditions in humans and other animals. For a more detaileddiscussion of this topic, see V-9039--Rats and Mice: Introduction andUse in Research, Part 1 (5).

9. Section title ANATOMY

10. Physical appearance

Rats and mice have short hair, long naked tails, erectrounded ears, protruding (exophthalmic) eyes, andpointed snouts with long whiskers (vibrissae). Bothspecies have five toes on the fore- and hindfeet, butthe first digit is reduced in size on the forefeet. Avariety of coat colors are found in rats and mice,including albino, solid colors, and hooded patterns.

11. Skeletal system

The vertebral formula of laboratory rats and mice isidentical and illustrated in this image of a ratskeleton. Bone maturation occurs slowly in theseanimals and ossification is not complete until near theend of the first year of life.


12. Oral cavity

This image of a rat skull illustrates the relativeposition of rodent teeth. Rats and mice havemonophydont dentition, that is, they have only oneset of permanent teeth. These teeth consist of twoincisors and six molars in both the upper and lowerdental arcades. The dental formula is: 2(l 1/1, C 0/0,P 0/0, M 3/3)= 16. The incisors are open rooted(hypsodontic) and erupt and grow continuouslythroughout life, while the molars are permanentlyrooted (brachiodontic) and do not continue to grow.

Tonsils are not present in the oropharynx of rats. 13. Normal incisors

This image shows normal rat incisors. The incisorsnormally grow, calcify, and erupt throughout life.Their occlusal surfaces are continuously worn downby abrasion at the point of apposition of the upperand lower incisors. The tips of the lower incisors arepositioned slightly posterior to the tips of the upperincisors, with each sharpened to a chisel-likeconfiguration by their integrated occlusion.

14. Overgrown incisors

This image shows a rat with overgrown incisor teethcaused by malocclusion. With malocclusion, the pointsof apposition of the occlusal surfaces of the upper andlower incisors are malaligned, the teeth fail to weardown, and they overgrow. Malocclusion may follow thefracture or loss of an incisor, inappropriate nutrition orsoft diets that do not contribute to normal tooth wear,genetic predisposition.

The overgrown teeth can be trimmed periodically to prevent damage to adjacent soft tissues buttrimming may not correct the malocclusion. If genetic predisposition is suspected, the colonyshould be selectively bred to eliminate the trait.


15. Nervous system

As shown in this image, the cerebral hemispheres ofrats and mice are smooth, lacking the folds andgrooves (gyri and sulci) seen in higher order species.The peripheral nervous system is composed of 34pairs of spinal nerves: 8 pairs of cervical, 13 pairs ofthoracic, 6 pairs of lumbar, 4 pairs of sacral, and 3pairs of caudal nerves.

16. Eye

The eyes of both rats and mice protrude from thehead, as illustrated by this normal rat. Consequently,the eyes are subject to injury and ulcers, scarring, oropacity of the cornea may be seen.

17. Vasculature of orbit

Mice have extensive periorbital venous sinuses behindthe globe of the eye, while rats have a more discreteplexus of vessels (7). These vascular structures areuseful for periorbital (orbital sinus) blood collection andpose less risk than cardiac blood collection in thesespecies. Following anesthesia, a heparinizedmicrohematocrit capillary tube can be inserted into themedial canthus of the eye until the bony orbit iscontacted, then withdrawn slightly to allow the blood toflow through the tube and into a collection vessel.


18. Harderian gland

The horseshoe-shaped Harderian gland (arrow) islocated within the bony orbit. Secretions from thisgland include the reddish pigment porphyrin, andhypersecretion in stressed rats is often referred to as“red tears” (chromodacryorrhea). These secretionsmay be observed around the eyes, around the naresafter passage through the nasolacrimal duct, or onthe forelimbs after the animal has groomed its face.Stressors may include disease, environmental,social, or experimental factors.

19. Lymph nodes-

Lymph nodes are located superficially,subcutaneously or between muscles; and deep,within the abdominal or thoracic cavities. They maybe difficult to palpate or to visualize in healthyanimals, but may be enlarged in animals withlocalized or systemic infections or in neoplasticconditions, such as lymphosarcoma illustrated in thisimage.

20. Thoracic viscera

This image of an opened rat thoracic cavity shows therelative positions of the lungs, the heart, and thethymus. A knowledge of the location of thoracicvisceral structures is valuable for accomplishing avariety of experimental techniques (i.e., thymectomy,pulmonary lobectomy, coronary arterial occlusion, andcardiac blood collection). The thymus has paired,triangular shaped lobes and is located ventral to thetrachea at the thoracic inlet. The gland is large inyoung animals, reaches maximum size at sexualmaturity, and then regresses in size.


21. Cardiovascular system

As seen in this image of a rat, the heart is locatedalong the midline of the thorax surrounded by the lobesof the lung. The apex lies close to the diaphragm(allowing cardiac puncture for blood collection, with theneedle inserted cranially next to the xiphoid process(squares)). Cardiac puncture can also be performed byinserting the needle between ribs 3 to 5 on the animal’sleft side. The vasculature is comparable to that in othermammalian species with the following exceptions: 1) rats and mice have two anterior vena cavae; 2) the right precava in rats empties directly into theright atrium, while the left precava joins the azygousvein and ultimately empties into the caudal vena cava; 3) both anterior / superior vena cavae in mice emptyinto the right atrium. 22. Lungs

This ventral view of the lungs shows the arrangementof lung lobes in the rat and the mouse: there is asingle left lobe, and four right lobes—the cranial,medial, caudal, and postcaval lobes. The trachea ofboth species is composed of incomplete,‘C’-shaped,cartilaginous rings extending from the larynx into thethoracic cavity. The trachea branches to form the leftand right bronchi, composed of completely circularcartilaginous rings.


23. Brown fat

Brown fat, referred to as the ‘hibernating gland’ ormultilocular adipose tissue, is present in rats andmice, despite the fact that they are not hibernatingspecies. The greatest accumulation of this pigmentedfat is found between the scapulae (arrows), but it canalso be observed in the axillary and cervical regions,along the jugular veins and thoracic aorta, at the hilusof the kidney, and along the urethra. Also note that thepigmentation may appear light, as in this photo, or as adarker brown. Although rats and mice are nothibernating animals, this tissue may serve as aneconomizer of proteins by ensuring utilization ofreserve carbohydrates and fats, and plays a major rolein thermogenesis during cold exposure (1).

24. Abdominal viscera

In this ventro-dorsal view of the abdominal viscera of amouse, the liver can be seen as the organ adjacent tothe diaphragm. The liver accounts for 4 to 5% of thetotal body weight in adults and is composed of fourlobes in both rats and mice. The median lobe, which isnot visible here, surrounds the gall bladder in mice. Therat has no gall bladder. The spleen lies along the greatercurvature of the stomach, and the small intestine is seenas a folded mass on the right side. The cecum originatesat the junction of the ileum and colon and is usually seenas an ingesta-filled blind pouch extending across to theleft side of the abdominal cavity.


25. Gross

In this image, the gastrointestinal tract of a rat hasbeen removed from the abdomen, the mesentery cutaway, and the individual structures labeled. Thesmaller view (inset) shows the more naturalarrangement. The cecum has a rumen-like function,with the resident microbes aiding in digestion ofcellulose and other plant materials. In germ-freeanimals, the cecum will become enlarged anddistended with ingesta. Though rat and mouse cecaelack a vermiform appendix, they both have a focalaccumulation of lymphoid tissue near the apex of thececum, analogous to the appendix in humans. Focallymphoid aggregates, Peyer’s patches, can be founddispersed along the length of the small intestine.

26. Dissected stomach

This image presents gross dissections of a ratstomach with portions of the esophagus andduodenum attached. The one on the right is filled withingesta; the one on the left has been opened andemptied. The esophagus in rodents is lined withkeratinized epithelium and is attached at the lessercurvature of the stomach, near the ‘limiting ridge.’ Thecardiac sphincter is located at the terminus of theesophagus. The stomach of rats and mice is dividedinto two regions, both grossly and histologically. Thenonglandular forestomach is lighter in color and thin-walled, compared with the pinker, thicker-walledglandular corpus that empties into the duodenum. A‘limiting ridge’ separates the two regions and preventsvomiting in rats but does not prevent ingesta frommoving freely from one side to the other. The pyloricsphincter is located at the junction of the stomach andthe duodenum


27. Urinary system

The urinary system is composed of the paired kidneysand ureters, the urinary bladder, and the urethra. Theright kidney and adjacent adrenal gland are locatedmore cranial than the left kidney. The kidney is classifiedas unipapillate, having one papilla and one calyx, whichenter the ureter directly. The urinary bladder is located inthe midline in the caudal portion of the abdomen andmust be avoided during intraperitoneal injections (inset).The urethra opens in the penis in males and in thegenital papilla near the base of the clitoris in females(rather than in the vagina or vestibule as is the case indomestic animals and humans).

28. Male genitalia

This view of the ventral surface of a male mouseshows the scrotum and genital papilla with relation tothe anus. The testes lie in the scrotal sac on bothsides of the ventral midline between the opening ofthe prepuce and the anus. The inguinal rings areopen throughout life, allowing the testicles to bewithdrawn into the abdomen. The penis is locatedwithin the genital papilla (prepuce), and contains abony process, the os penis.

29. Male accessory sex glands

The accessory sex glands and urogenital system of amale mouse are shown in this image. The largestaccessory male sex glands are the paired, elongated,curved vesicular glands, often referred to as theseminal vesicles, which empty into the urethra nearthe neck of the bladder. The coagulating glands arelocated within the lesser curvature of the seminalvesicles. The view on the right shows the prostategland which has two pairs of lobes, dorsal and ventral,and the paired bulbourethral glands. The prostategland is located along the body of the penis. Themixture of fluids from these glands forms the vaginal(sperm) plug. Rats and mice may be castrated forexperimental endocrine and other studies.


30. Female genitalia

This image illustrates the external genitalia of femalerats and mice, consisting of the genital papilla,containing the clitoris and urethral orifice, and thevulva, containing the vaginal opening. A vaginalclosure membrane is usually present in immaturefemales and disappears prior to sexual maturity. Theanogenital distance (from the genital papilla to theanus) is shorter in females than in males.

31. Female reproductive system

This dissected specimen of the female urogenitalsystem of a rat demonstrates that the ovaries areclose and slightly caudal to the kidneys and usuallyembedded in fat. The uterus is bicornuate, that is, ithas two horns that merge into the body of the uterus.The rat has two cervices, one for each horn, while themouse has only a single cervix at the junction of thebody of the uterus and the vagina. The uterus andovaries lie close to the dorsal body wall, allowing adorsolateral approach for removal of the ovaries oruterus (ovariectomies and ovariohysterectomies) for avariety of research purposes. The vagina is a shortcanal leading to an opening caudal to the genitalpapilla and cranial to the anus. The types of cellspresent in a vaginal smear can help identify thecurrent stage of the estrous cycle of the female. Thelarge size of the pronucleus in the ovum of the mousefacilitates microinjection procedures for transgenicmouse production.

32. Mammary tissue

As these illustrations show, rats have six pairs ofnipples; mice have five pairs. Mammary tissue iswidely distributed in both species and may extend uponto the lateral and dorsal areas of the abdomen andthorax. It is, therefore, possible to find mammarytumors on the back of a female.


33. Gender identification of neonates

As seen in this image, one can identify the gender ofneonates by comparing the relative distance betweenthe genital papilla and the anus, referred to as theanogenital distance, which is greater in males.

34. Section title PHYSIOLOGY

35. Normative data

This image shows the physiologic parameters foradult rats and mice. (Refer to Appendix I foradditional values.) Some variations among thesevalues may occur between groups of rodents due tostock or strain differences, source of the animals, andresearch conditions.

36. Diet

The composition of the diet fed to laboratory animals isof major importance in maintaining them in good healthand yielding consistent data. In experimental studies ofnutrient excess and deficiencies, rats have been usedmuch more frequently than mice and much more isknown about their nutrient requirements. Experiencehas proved, however, that both rats and mice can bemaintained satisfactorily on a low fiber diet (5 %) andare typically fed a commercially pelleted diet referred toas “rodent chow” (3). Rats consume approximately 5 gper 100 g of body weight in food daily and mice 12 gper 100 g of body weight per day.


37. Types of diet

Rodents can be fed a pelleted diet or a powdered(mash) diet. The pelleting process requires heat thatmight adversely affect chemicals being studied, buttest chemicals can be mixed into mash diets forresearch purposes. Barrier conditions andmaintenance of immunocompromized animals (i.e.,SCID or nude mice, transgenic animals) may requirethat caging, bedding, water, and feed be autoclavedso that animals are not exposed to infectious agents.Autoclaving can also affect levels of nutrients withinthe diet, therefore, commercially availableautoclavable chow is formulated with higher levels ofvitamins to ensure that an adequate level of vitaminswill remain after autoclaving. It is beneficial topurchase rodent chow from feed manufacturersproducing “open-formula diets” composed of naturalproducts but with specification of the exact ingredients(2). The nutritional consistency of these diets over timeeliminates one variable in the research process.

38. Water

Fresh, clean water free from bacterial or chemicalcontamination should be available ad libitum. Ratsconsume approximately 10 ml/100 g of body weightper day; mice consume 1.5 ml/10 g of body weightper day. Water can be delivered to animals via waterbottles or through an automatic watering system.

39. Life span and Rats generally live for two to three years, but some that were fedcalorically restricted body weight diets lived longer (8). The life span ofmice is usually two years. Mice maintained in a pathogen-freeenvironment may outlive others raised and housed in conventionalenvironments because they are not exposed to the detrimental effectsof subclinical diseases. Adult male rats weigh 300 to 500 g andfemales weigh 250 to 300 g. Male mice will weigh 20 to 40 g atmaturity and females 25 to 30 g. (See Appendix 2 for additionalparameters.)


40. Sexual maturity The age at puberty varies between the species, strain or stock of ratsand mice. In general, rats reach puberty around 50 to 60 days of age,while mice reach puberty around 28 to 49 days of age. The first fertilemating in mice generally occurs around 7 to 10 weeks of age, whilerats are usually bred after 9 weeks of age.

41. Section title REPRODUCTION

42. Estrous cycle

Rat and mouse females are polyestrus, breedingthroughout the year. They exhibit regular estrouscycles, lasting approximately 5 days in the rat, and 4to 5 days in the mouse. Estrus or ”heat,” the period ofsexual receptivity of the female, usually occursspontaneously at night after day 3 of the cycle andlasts for 12 to 14 hours. Ovulation occursspontaneously within 8 to 12 hours after the onset ofestrus.

43. Cell monitoring of estrous cycle

The stages of the estrous cycle can be determinedby performing daily vaginal lavage using sterilesaline(shown) and microscopically examining the celltypes during the cycle (staining with methylene bluewill facilitate identification of cornified epithelial cellspresent during estrus). This procedure facilitatesbreeding of animals on the day of ovulation andproducing timed-pregnant animals of knowngestational age of the fetuses.

44. Mating When indicators of ovulation are detected by vaginal cytologic examination, females are placedwith males for breeding. Receptive females exhibit lordosis, a rigid posture with the hindquarterselevated when downward pressure is applied to the pelvis (as demonstrated by the female at thetop). Mating usually occurs during the dark phase of the photoperiod. Increasing the light phaseof the photoperiod to 14 hours per day enhances mating and reproductive rates. Females canalso be bred during a postpartum estrus that occurs between 14 and 28 hours after parturition.


45. Vaginal plug

Successful mating in rats and mice is verified by thepresence of a vaginal plug in the females. The vaginalplug is formed from the mixing of vesicular andcoagulating gland secretions at the time of ejaculation.Vaginal plugs may be retained in mice for 16 to 48hours, but often fall out of rats within hours afterbreeding. Direct observation of the vaginal plug in thevagina or its presence in the waste pan beneathsuspended wire caging is a good indication thatmating took place. Another technique utilized to detectmating is vaginal lavage and microscopic examinationfor the presence of sperm. Presence of the plug doesnot guarantee that an animal is pregnant, thus matedanimals should be observed and later palpated toconfirm pregnancy.

46. Gestation / parturition

The length of the gestation period may vary with thestrain or stock of animal. The range in rats is from 21to 23 days (usually averaging 21 days) and 18 to 21days in mice (19 day average). Periodic stretchingand extension of the hindlegs signals impendingparturition; for delivery, females stand in a semi-crouched position. Fetuses are delivered with eitherhead or breech presentation. The female usually eatsthe placenta, then turns her attention to the pups.Delivery of all pups may take 1 to 4 hours.


47. Section title BEHAVIOR

48. Handling

Rats and mice are nocturnal and, if disturbed duringthe daytime, may bite the handler. Both rats and micecan be “gentled” by careful handling when they arevery young. Once gentled, they are easier to handleduring husbandry and research procedures and lessstressed by the handling. Animals familiarized withhandling or experimental procedures have a higherpain tolerance threshold, and are less stressed byexperimental conditions. The Guide discourages longterm restraint of animals because it is stressful.Biotelemetry systems and tether systems can beutilized to allow greater freedom of movement foranimals with minimal distress.

49. Fight wounds

Male mice housed together may fight and may beinjured or killed. If the aggressor is removed andhoused individually, fighting is reduced or stopped.Male rats are less inclined to fight when groupedtogether.

50. Behavior

Some dominant females may groom their cage matesexcessively or nibble their hair, referred to asbarbering (shown in this image). This form of hair lossmust be differentiated from endocrine or parasiticcauses of hair loss. Both rats and mice are sensitive topheromonal changes within their environments, andchanging bedding or introducing new animals into theroom may affect the behavior and physiology of theinhabitants. Other physical, biological, and socialfactors can influence experimental integrity byaffecting food and water consumption, reproductiveperformance, drug metabolism and other alteredphysiologic parameters (6).


51. Conclusion This concludes this autotutorial session on the biology and use inresearch of rats and mice. There are six programs in this series:• V-9040 RATS AND MICE: Use in Research• V-9041 RATS AND MICE: Biology• V-9042 RATS AND MICE: Care and Management• V-9043 RATS AND MICE: Bacterial and Mycotic Diseases• V-9044 RATS AND MICE: Viral Diseases• V-9045 RATS AND MICE: Parasitic Diseases

52. ACLAM creditsThis program was developed for the

American College of Laboratory Animal Medicine.G. L. Van Hoosier, Jr., DVM, Chair

G. L. Borkowski, DVMK. R. Boschert, DVM

J. F. Harwell, Jr., DVMJ. M. Linn, DVM

C. W. McPherson, DVMA. F. Moreland, DVM

G. M. Otto, DVMC. A. Pekow, DVM

Instructional development, editing, and production managementprovided by Barbara Macfadden

andgraphic illustrations by B. J. Meredith.

The development of this program was supported by a grant from theDuPont Merck Pharmaceutical Company.

53. HSCER creditsProduced by the

Health Sciences Center for Educational ResourcesUniversity of Washington

Seattle WA 981952000


REFERENCES

1. Bivin, W. S., M. P. Crawford, and N. R. Brewer. 1979. Morphophysiology, p. 73-103. In H.J. Baker, J. R. Lindsey, and S. H. Weisbroth (ed.), The laboratory rat, vol. I.Academic Press, Inc., New York.

2. Knapka, J. J., K. P. Smith, and F. J. Judge. 1974. Effect of open and closed formularations on the performance of three strains of laboratory mice. Lab. Anim. Sci. 24:480-487.

3. National Academy of Sciences and National Research Council. 1978. Nutrientrequirements of laboratory animals. National Academy of Sciences, Washington, D.C.

4. National Research Council. 1980. Survey of laboratory animal facilities and resources,fiscal year 1978, p. 32. National Institute of Health publication no. 80-2091.

5. Porter, P. P. 1993. Rats and mice: introduction and use in research, part I [images].American College of Laboratory Animal Medicine, University of Washington, Seattle,Wa.

6. Rowan, A. 1991. Refinement and rodents: a report concerning the well-being of laboratoryrodents. Tufts Center for Animals & Public Policy, North Grafton, MA.

7. Timm, K. I. 1980. Peri-orbital bleeding technique for the mouse, hamster, and rat --anatomical consideration. Synapse. 13(1):14-15.

8. Wu, B. P. 1994. How diet influences the aging process of the rat. Proc. Soc. Exp. Biol. Med.205(2):97-105.


BIBLIOGRAPHY

Baker, D. E. J. 1979. Reproduction and breeding, p. 153-168. In H. J. Baker, J. R. Lindsey, andS. H. Weisbroth (ed.), The laboratory rat, vol. I. Academic Press, Inc., New York.

Cook, M. J. 1983. Anatomy, p. 101-120. In H. L. Foster, J. D. Small, and J. G. Fox (ed.), Themouse in biomedical research, vol. III. Academic Press, Inc., New York.

Cunliffe-Beamer, T. L., and E. P. Les. 1987. The laboratory mouse, p. 275-308. In T. Poole(ed.), The UFAW handbook on the care and management of laboratory animals. LongmanScientific & Technical, Essex, England.

Festing, M. F. W. 1979. Inbred strains, p. 55-72. I H. J. Baker, J. R. Lindsey, and S. H. Weisbroth(ed.), The laboratory rat, vol. I. Academic Press, Inc., New York.

Festing, M. F. W. 1987. Introduction to laboratory animal genetics, p. 58-84. In T. Poole (ed.),The UFAW handbook on the care and management of laboratory animals. Longman Scientific &Technical, Essex, England.

Hebel, R., and M. W. Stromberg. 1976. Anatomy of the laboratory rat. Williams & WilkinsCompany, Baltimore.

ILAR. Fall 1979. Laboratory animal management: genetics. ILAR News. 23(1):A1-A15.

Jacoby, R. O., And J. G. Fox. 1984. Biology and diseases of mice, p. 31-89. In J. G. Fox, B. J.Cohen, And F. M. Loew (Ed.), Laboratory Animal Medicine. Academic Press, Inc., New York.

Kohn, D. F., and S. W. Barthold. 1984. Biology and diseases of rats, p. 91-122. In J. G. Fox, B.J. Cohen, and F. M. Loew (ed.), Laboratory animal medicine. Academic Press, Inc., New York.

Olds, R. J., and J. R. Olds. 1988. A colour atlas of the rat - dissection guide. Wolfe MedicalPublications Ltd., Ipswich, England.

Popesko, P., V. Rajtova, and J. Horak. 1990. A colour atlas of the anatomy of small laboratoryanimals. In Rat, Mouse, Golden Hamster, vol. 2. Wolfe Publishing Ltd.

Rogers, A. E. 1979. Nutrition, p. 124-152. In H. J. Baker, J. R. Lindsey, and S. H. Weisbroth(ed.), The Laboratory rat, vol. 1. Academic Press, Inc., New York.

Staats, J. 1981. Inbred and segregating inbred strains, p. 177-213. In H. L. Foster, J. D. Small,and J. G. Fox (ed.), The mouse in biomedical research, vol. I. Academic Press, Inc., New York.

Weihe, W. H. 1987. The laboratory rat, p. 309-330. In T. Poole (ed.), The UFAW handbook onthe care and management of laboratory animals. Longman Scientific & Technical, Essex,England.


APPENDICES

APPENDIX 1

NORMAL PARAMETERSRats Mice

Lifespan 2-3 years 2 yearsBody Temperature 97-102°F (99.5°F) 95-102.5°F (97.5°FHeart rate 330-480 bpm 320-780 bpmRespiration 66-114/min (85/min) 84-280/min (163/min)Urine volume 3.3/100g body wt/day 0.5-1.0 ml/ dayTotal BTU/hour/animal 4.3 0.6Body weight 250-500 g 25-40 g

APPENDIX 2

NORMAL ADULT PARAMETERSRats Mice

Age at puberty 50-60 d 35dMinimum breeding age 55-90 d M~60 d; F~50-60dFood consumption 5g/100g bwt/d 12g/100g bwt/dWater consumption 10ml/100g bwt/d 1.5ml/10g bwt/dMature body weight M~300-500g M~20-40g

F~250-300g F~25-30g


NOTES

rats and mice

Documents